2. 职称英语
  3. If y = 3x and z = 2y, what is x + y + z in terms of x ?A、10xB、9xC、8xD、6xE、5x

If y = 3x and z = 2y, what is x + y + z in terms of x ?A、10xB、9xC、8xD、6xE、5x

游客2024-01-12  16
问题 If y = 3x and z = 2y, what is x + y + z in terms of x ?
选项 A、10x
B、9x
C、8x
D、6x
E、5x
答案 A
解析 It is not necessary to find the individual values of x, y, and z to answer the question. You are asked to rewrite the expression x + y + z as an equivalent expression in terms of x. This means that you need to use the information provided about y and z to express them in terms of the variable x. The variable y is already given in terms of x; that is, y = 3x; and because z = 2y, it follows that z =(2)(3x)= 6x. Using substitution, you can rewrite the expression as follows.
x + y + z=x +(3x)+(6x)
=(1 +3 + 6)x
=10x
The correct answer is Choice A.
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